In [1]}, [2]} it was found that in Jewel with four-momentum subtraction the jet mass was significantly larger than observed in data. Following the discussion in section  we conclude that four-momentum subtraction yields problematic results for jet mass and expect constituent subtraction to be much more reliable.
ALICE measured the charged jet mass in three different jet \(p_\perp \)  bins [1]}. With four-momentum subtraction charged jets pose a problem, since it subtracts parton level momenta from hadron level jets. The workaround was to reconstruct and subtract full jets, and afterwards rescale the jet \(p_\perp \)  and mass with factors derived from jets with the same cuts in p+p collisions. The results (including only jets with positive squared mass) are shown as the orange histograms in figure REF  and clearly don't agree very well with the ALICE data. Using event wise constituent subtraction with the same procedure of rescaling full jets (green histograms in figure REF ) leads to an improvement, but still not a satisfactory description of the data. The best agreement with data is obtained by doing event wise constituent subtraction preserving the particles' flavour, such that charged jets can be reconstructed in the background subtracted event (blue histograms in figure REF ). The jet mass distribution calculated in this way is shifted slightly towards smaller masses compared to the p+p distribution. This is due to a partial cancellation of the jet collimation effect and medium response. Jet collimation leads to a reduction of the mass (a small mass is correlated to a narrow and hard fragmentation pattern), while medium response increases the mass by adding soft particles distributed widely over the jet (and beyond).
